modification new pipe

[elowami]

In our company we need to connect the boil off gas line to relief line.

is this modification need to vent or drain? and what is the main factors in this type of work?

Thanks for your participation.

 

[Sina]

I think you want to joint these two pipe with welding if so, purging is necessary to avoid explosion. after purging if LEL is lower than explosion limit, you can weld.

 

[elowami]

your answer is not clear.

my question is:
is this modification (line) required vent or drain or both?

thank you

 

[met11]

Well if you're going to be hydrotesting the line in place, the fabricator may be grateful for a vent and a drain. If the pipe can't become vapor-locked, then you probably don't need a vent. If it can free-drain back to the boil-off line and there's a drain there, you may not need a drain.

If there is a pocket, you might want a drain. A high point pocket? Probably need a vent. Isolation valves? Might want vents and drains for maintenance. Is the line made of Tantalum? If so you might want to minimize valves.

Basically... how could anyone know with the information you provided?